I think that Arnold becoming a traitor from the day things started to go downhill for him. It started when Arnold and his sister Hanna were the only children to live to adulthood due to yellow fever. After that Arnold's Father's barrel company went out of business, causing him to come home from his boarding school due to lack of money. Tragically, while at boarding school Arnold’s mother had died, and his father had turned to drinking to solve all his problems. This left Arnold with only his younger sister and a ruined family name. Then Arnold and with the help of his sister opened an apothecary shop that helped repay some of the debt made by his father. Arnold also left of voyages and left his sister in charge of the shop during his absences. Then he became a part of a secret organization called the "Sons of Liberty." In February 1767 he married Margaret Mansfield the daughter of the sheriff of New Haven. Arnold and Margret then had three sons : Benedict, Richard, and Henry. From there he left his family and helped make the capture of fort Ticonderoga, almost captured Quebec on an epic march, and was promoted to the rank of general. Unfortunately while gone his wife died leaving his sister to care for his three sons’, and in-charge of the shop. I think this along with the other things that happened earlier in his life caused him to betray the US, and after congress humiliated Arnold by rejecting him from being promoted to major general he probably felt like there was no reason for him to stay with America. Also Arnold was in debt because of the house he bought and because of the extravagant gifts he would give to his second wife, so money did play a large role in his betrayal. Once he took A hold of West Point and almost gave up a major US base, I think that was so unhappy with his life that he felt he could do better if he left the US, and started over, so that is why I think Arnold left America for the British.